Degradation of water soluble poly(vinyl alcohol) with acoustic and hydrodynamic cavitation : laying foundations for microplastics

Petkovšek, Martin (author), Kržan, Andrej (author), Šmid, Alenka (author), Žagar, Ema (author), Zupanc, Mojca (author)

Water-soluble poly(vinyl alcohol) (PVOH) is widely used in the textile and paper industries and in households as detergent pods. In addition to conventional microplastics, water-soluble PVOH poses an environmental threat because it is usually washed down the drain unnoticed and unobstructed. If not treated during wastewater treatment, it enters the aquatic ecosystem in estimated quantities of several thousand tons annually. The present study aims to address the degradation of PVOH on a laboratory scale by acoustic and hydrodynamic cavitation, assisted or not with an oxidative agent. A hydrodynamic cavitation generator, designed with consideration for real-life application, presents an innovative technology adapted for wastewater treatment. The effects of temperature, addition of external oxidant, and methanol as a hydroxyl radical ($^•$OH) scavenger to PVOH solutions were systematically studied. At optimal operating conditions, PVOH molar mass averages significantly decreased (from weight average molar mass of 124 to 1.6 kg mol$^{−1}$ in case of 60 min treatment with hydrodynamic cavitation and addition of external oxidant) with concomitant narrowing of molar mass distribution. The SEC/MALS, FTIR, and $^1$H NMR results show that mechanical degradation of PVOH chains predominates in acoustic cavitation, while chemical effects also play an important role in hydrodynamic cavitation. Findings from this study could serve as model research for the degradation of other carbon-backbone polymers and provide a route to improved ultimate (bio)degradation of functionalized polymers in the environment.

• Language: English
• Keywords: cavitation, PVOH, microplastics, degradation, mechanical engineering, pollution remediation
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering; FFA - Faculty of Pharmacy
• Publication status: Published
• Publication version: Version of Record
• Year: 2023
• Number of pages: 11 str.
• Numbering: Vol. 6, art. 35
• PID: 20.500.12556/RUL-145650
• UDC: 532.528:678.7
• ISSN on article: 2059-7037
• DOI: 10.1038/s41545-023-00248-8
• COBISS.SI-ID: 150832899
• Publication date in RUL: 04.05.2023

Record is a part of a journal

• Title: npj clean water
• Shortened title: npj clean water
• Publisher: Springer Nature, King Fahd University of Petroleum & Minerals
• ISSN: 2059-7037
• COBISS.SI-ID: 529633561

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: kavitacija, PVOH, mikroplastika, razgradnja